.tab{
    width: 500px;
    height: 500px;
    margin: 50px auto;
    border:1px solid #000;
}

.tab .nav{
    height: 50px;
    border-bottom: 1px solid #000;
}

.tab .nav-item{
    float: left;
    width: calc(100% / 3);
    height: 100%;
    text-align: center;
    line-height: 50px;
}

.tab .nav-item.current{
    background-color: #000;
    color: #fff;
}
.tab .page{
    position: relative;
    height: 450px;
}
.tab .page-item{
    display: none;
    position:absolute;
    left: 0px;
    top: 0px;;
    width: 100%;
    height: 100%;
    text-align: center;
    line-height: 450px;
    font-size: 100px;
}

.tab .page-item.current{
    display: block;
}
